A school-going boy of about 10 years age presented with enlarged painful axillary lymph nodes. The doctor also noticed a small inflamed circular coin-like lesion surrounding a small abraded area on the forearm.
The inflamed lymph node was aspirated and the aspirate was submitted for laboratory studies. A Warthin-Starry Silver Impregnation Staining of the smear prepared from the lymph node aspirate revealed plenty of pleomorphic rod shaped organisms. Routine cultures were negative.
The sample was also inoculated on Chocolate agar and incubated in CO2 (5%). Growth was observed after about a week. The colonies are white dry cauliflower-like and embedded in agar. Smear from the culture revealed small, slightly curved Gram negative bacilli. The bacilli are motile.
(Image source : http://graphics8.nytimes.com/images/2007/08/01/health/adam/8989.jpg accessed on 1st September 2009)
(Warthin-Starry Silver Impregnation Staining )
1. What is the most likely diagnosis.
2. What could be the causative organism.
3. What additional information from the patient's history will be beneficial in arriving at a diagnosis.
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Correct answers submitted by :
Dr. Sarita Kar
Dr. Saileela K
1. The Most likely diagnosis is Cat scratch disease.
2. The most likely causative agent is : Bartonella henselae
3. Additional histoy about exposure to cat or dog's scracth or bite would be helpful to arrive at the diagnosis.